you may be retaining water because you're not drinking enough, on the atkins diet you need to drink approx 4 litres of water to flush the ketones and by products of fat burning out of your liver and kidneys, also if it's near (that time of the month...) you can store up to 7lbs in fluid pre period. Also, (sorry to bore you lol) if you buy some ketostix (from the chemist or ebay) and wee on them, if they are pink/purple it means your body is in ketosis (fat burning mode) so if you feel like you're not losing weight it's a motivator to know you are in ketosis. You'll probably find your weight will WHOOSH down on your next weigh in xx